Aliphatic diisocyanate finish additive

ABSTRACT

Aliphatic diisocyanates as adhesion promoting agents are added to the finish or spinning composition applied to tire yarn used in making tire reinforcing cord as a means of promoting adhesion between the cord and the rubber when using a conventional R/F/L adhesive.

United States Patent 1191 Bhakuni et a1.

[ ALIPHATIC DIISOCYANATE FINISH ADDITIVE [75] Inventors: Roop S, Bhakuni, Copley; Joseph L.

Cormany, Jr., Akron, both of Ohio [73] Assignee: The Goodyear Tire and Rubber Company, Akron, Ohio [22] Filed: Oct. 29, 1971 [21] Appl, No.: 193,992

Related US. Application Data [63] Continuation-impart of Ser. No. 78,251, Oct. 5, 1970.

52 us. c1 252/85,.6, 57/153, 57/164, ll7/138.8 F, 117/1395 co,117/139.5 A,

151 1 Int. Cl D06m 13/42 581 Field or Search 252/86; 156/110 A, 156/161, 331; 117/1395 co. 139.5 A, 138.8

[ 1 Aug. 28, 1973 Primary Examiner-Herbert B. Guynn Attorney-F. W. Brunner and V. G. Parker ABSTRACT Aliphatic diisocyanates as adhesion promoting agents are added to the finish or spinning composition applied to tire yam used in making tire reinforcing cord as a means of promoting adhesion between the cord and the rubber when using a conventional R/F/L adhesive.

1 Claim, No Drawings ALIPHATIC DIISOCYANATE FINISH ADDITIVE This application is a continuation-in-part application of our application Ser. No. 78,251 filed Oct. 5, 1970.

This invention relates to an improved tire yam finish. and to an improved laminate of rubber reinforced with a cord made of the yarn coated with the finish containing an adhesion promoting agent which promotes a bond between the cord and the rubber as in a,pneuma-, tic tire when using a conventional RIF/L adhesive ap plied, to the finish treated. cord prior to. embedment in the rubber.

Pneumatic tires are being subjected to increasingly severe operating conditions, especially highspeeds, heavy loads, and accelerated braking and, the performance of the tire under these conditions depends in large part upon the durability of the, adhesive bond developed between the reinforcing cord and the rubber being reinforced. The bond is formed between activesites in the rubber and on the surface of'the cord. The

filaments in the yarn used in making the cord are coated with a finish to provide proper lubrication during the drawing and twisting operations in making the cord. It has been observed that the finish interferes with maximum bonding of the cord to, the rubber.

It has now been discovered that this, difficultycanbe overcome without loss of any function performed by the finish by adding an adhesion promoting agent to the finish.

Even though the adhesion promoting agent is added to the finish, the finish still achieves a satisfactory lubrication of the filaments with a minimum of friction throughout various drawing, spooling', winding, transporting, twisting, cording, weaving and similar textile operations while still providing improved bonding between the cord and the rubber.

It is especially desirable to apply this adhesion promoting agent to the finished immediately after the filaments have been spun from, for example, molten polyester and'before stretching or fiber orientation of the polyester in a conventional manner as by dipping, spraying, or padding. Thereafter the yarn is heated over hot rolls at about 160 C. to about 255 C. in steps normally required for drawing and heat setting the filaments. The filaments are then made into a tire cord and a modified resorcinol/formaldehyde adhesive dip (RIF/L) is applied in a conventional manner to the cord.

The tire yarn finish base coating composition of this invention may be applied to many types of tire yarn including such natural fibers as cotton, regenerated cellulose fibers such as rayon, synthetic fibers such as polyamides and known generally as nylon, synthetic fibers of polyacrylonitrile generally known as acrylon, and synthetic fibers of polyesters, specifically fibers of polyethylene terephthalate known generally by the trade names Dacron, Vycron, etc.

Finishes useful in this invention are those used in the fiber industry primarily as a lubricant to minimize friction between the filaments and metal rolls during the drawing operation. Generally these finishes comprise a lubricating oil, an antistatic agent, and an emulsifier. The lubricating oils include such substances as palm oil, coconut oil, cottonseed oil, mineral oil, glyc'erides, polyglycol esters, butyl stearate, octyl stearate, esters of oleic acid, trimethylol propane/caprylic acid esters, 2-methyl-2-propyl-propane diol-l,3-dilaurate and 2-ethyl-2-butyl-propane diol-l,3-dilaurate. These lubricants are dispersed in water preferably with the aid of an emulsifying agent including such surface active organic compounds as the polyethoxylate of fatty acids, higher fatty alcohols, sorbitol esters or sorbitans, phosphate esters, sulfonated aromatic petroleum hydrocarbons, sulfonated naphthenates, sulfated vegetable oils, polyoxyethylene esters and ethers, polyglycerol esters and glycerol mono-difatty acid esters.

The finish may also contain an antistatic agent to re-. duce the electrostatic charge of the filament during its processing into a cord or fabric. Examples useful in this invention include such, cationic agents as quaternary ammonium-., pyridinium-, imidazolinium-, and quino-, linium function, phosphated alcohols and ethoxylated amides.

Water miscible organic solvents suchas benzene may also be used in forming the finish for such lubricants as paraffin oils, i.e., saturated aliphatic hydrocarbons boiling in the gasoline range.

The nonionic emulsifying agents" are preferred to in detail by Swartz et al in Surface Active Agents published by lnterscience Publications Incorporated (1949) starting at page 2 02, and their use with textile lubricants is describedin detail by Swartz etal. in Sur face Active Agents and Detergents, Volume II, by Interscience Publication Incorporated (1958) starting at page 596. The terms fatty acids" and fatty alcohols used in connection with describing the emulsifying agents refer to fatty acids and their corresponding alcohols having an aliphatic hydrocarbon chain of from C-8 to C-l8 or-more and are usually derived from natural sources and are usually mixtures of various chain length but the corresponding synthetic compounds may also be used.

The finish is prepared generally by mixing a blend of the lubricating oil with water to a 25 percent solids concentration and then adding the adhesive bond promoting agent to the oil-water mixture, or to the oil prior to mixing with water, and forming an emulsion thereof in warm water and adding sufficient alkali if necessary to adjust the pH from about 8.3 to about 8.5.

It has been found that an aliphatic diisocyanate will produce the desired improvement in bond strength between the rubber. and the polyester tire cord when added to the finish.

The long chain aliphatic diisocyanate having the general formula O=C=N[D]N=O where D is a 36 carbon hydrocarbon aliphatic radical having a molecular weight of 600 and an NCO content of 14 percent and sold under the trademark DD! and herein referred to as DDI(36C) and combinations thereof with tris [l-( 2- methyl) aziridinyl] phosphine oxide herein referred to as MAPO may be used as a finish adhesion promoting additive.

The adhesion promoting agent is added to the finish in amounts from about 0.05 parts to about 30 parts per parts by weight of lubricating oil present. The finish when applied to the filament is present in an amount between about 0.3 to about 1.5 parts per 100 parts of filament; The adhesion promoting agent may be added to the finish by blending into the oil or by blending into the water before or after the oil is added to the water or dissolved in a solvent and then blended into the oil. The pH of the mixture is to be adjusted as noted before depending upon the adhesion promoting agent and emulsion stabilizer used.

The proportions of the components of the tire yarn finish of this invention may vary over a wide range. In general, finish compositions may be present in the following general amounts based on the total solid presfil'lt.

Amount Ingredients Preferred Range Lubricant 70% 60-70% Antistatic agent 20% -30% Emulsifier 10% 10-20% The finish composition is applied to the tire yarn at a point below the spinneret in the form of a dilute aqueous emulsion, the concentration of which is varied as desired in accordance with the amount of finish to be applied to the yarn. The dried yarn may contain from about 0.3 to 1.5 percent by weight of the yarn of the finish composition.

A polyethylene terephthalate filament was coated in each instance with the finish containing the adhesion promoting agent by a scotch roll using a 25 percent solids emulsion of the finish on the filament at a point below the exit end of a 190 hole spinneret. The filaments are then spun at a spinning speed of 150 yards per minute to give a single spun yarn having a total denier of approximately 7,800, which yarn is then passed to a pair of rotating heated rolls and then passed around a pair of heated draw rolls rotating at a speed to impart a draw ratio of about 6 to 1 to give a total denier of approximately 1,300 and then wound on a bobbin. The yarn is plied 8 turns per inch, 3 plies are then twisted in reverse direction 8 turns per inch to form a cord referred to as 1,300/3,8/8.

The polyester cord having the modified finish of this invention is then treated with a 20 percent solids dispersion of a conventional R/F/L adhesive composition made in accordance with the following fonnula in amount sufficient to give a dry solids pick up of from 6 to 7 percent.

R/F/L Adhesive Ingredients Parts Resorcinol 98 Formaldehyde (37%) 53 Terpolymer rubber latex of styrene/butadiene- 1,3/vinylpyridine /70/15 (41%) 1152 Water 543 The R/F/L adhesive composition was prepared by adding 98 parts of the resorcinol to 196 parts of water, followed by the addition of 53 parts of formaldehyde. The resulting mixture was aged for one hour and then 1 152 parts of terpolymer rubber latex was added. The resulting mixture was aged for a period of 72 hours. After aging, the balance of the water was added. To 65 parts of this R/F/L composition was added 35 parts of a resinous formula: 1 10 parts of resorcinol, 25 parts by volume of formalin (37 percent formaldehyde in methanol and water), and parts by volume of water was reacted together in a reaction vessel equipped with both heating and cooling coils, a reflux condenser and a suitable agitator. The mixture was heated to reflux temperature (100 C.) and allowed to remain at this temperature for 15 minutes, after which an additional 30 parts by volume of formalin was added to the reaction mixture over a period of 10 minutes. After being refluxed for an additional 30 minutes, the resin formed in the reaction vessel was allowed to cool to room temperature. A thick, syrupy resin (for convenience referred to as Resin A) containing percent solids, a viscosity of 750 cps. and a pH of 7 was obtained.

Twenty parts of the Resin A described above is reacted with 6 parts of polymethylene polyphenylisocyanate for 48 hours at 72 F. At the end of this time, the resulting reaction mixture is treated with 0.1 part of sodium hydroxide and 100 parts of water. The resulting neutralized resin-blocked polyisocyanate was allowed to age for 8 hours to produce a clear supernatent layer of soluble resin-blocked polyisocyanate (and for convenience to be referred to as Resin B).

To parts of the R/F/L adhesive composition described above is added 35 parts of Resin B and allowed to age at 72 F. for 4 hours.

The polyester cord 1300/3 (Dacron) is passed through a dip tank containing this adhesive. The dipped cord is then dried at 450 F. and embedded in rubber compounded as shown below.

Parts by Weight Ingredients Amount May be used Used 1. Natural Rubber 0100 2. OE/SBR 1778 (styreneIputadi Zne-IJ l 23.5/76.5 co lymer) (p us 37 parts oi per SBR) p0 27.5 100-0 3. Cis 1,4-polybutadiene 10 0-50 4. Carbon Black (Reinforcing agent) 40 25-100 5. Zinc Oxide (Activator of cure) 4 2-10 6. Stearic Acid (Activator of cure) 2 1.5-3.0 7. Primary Accelerator (2,2'-dithiobisbenzothiazole) 1.25 .5-3.0 8. Pine Oil (Sofiener) 10 2-50 9. Secondary Accelerator (Tetramethyl thiuram disulfide) .10 .05-1 .0 10. Antioxidant .60 .l-4 l l. Sulfur (Vulcanizing agent) 2.5 1.0- 5.0

In compounding the rubber stock in accordance with the formulation set forth above, a masterbatch of ingredients l and 2 are made with the carbon black and mixed on a mill to a temperature of about 1 10 C. and may be mixed at a temperature as high as C. The resulting carbon black masterbatch is then cooled and the remaining compounds are mixed into the batch in the order indicated above to a temperature of about 70 C. and may be mixed at a temperature as high as 100 C.

The following ratings are based on a control using the identical finish, cord and rubber but without the addition of an adhesion promoting agent to the finish. Amount of additive is in percent by weight based on the total weight of the finish solids present in the finish.

Amount Rating Example Additive Percent Peel Force (1) Fatigue (2) l. DDI(36C) 2.0 117 I95 2. DD] (36C) 1.5} 112 MAPO .5 3. DDI (36C) 4.0}

MAPO .5

(I) Feel adhesion is determined in the following manner. Onto the surface ofa12 mil thick sheet (12" X 12") ofrubber (MRS) is laid the treated cords at the rate of 18 per inch which are then covered with a second sheet (12" X 12") of 12 mil gauge rubber (MRS). This "sandwich" arrangement of rubber cord and rubber is then doubled onto itself with a piece of Holland cloth extending one inch into the doubled assembly from the open end from which assembly is clicked 1" X 3 samples, which samples are then cured in a mold at 340 F. for 10 minutes. The cured sample is then laced in an Instron machine, heated at 250F.andthetwostripsofru rseparatedbytheI-Iollandcloth are then moved in opposite directions at the rate of 2" per minute to determine the average force (A) required to swarate the remaining portion of the sample. Depending on the adhesion developed between thecord and rubber, separation either occurs at the rubber/rubber interface or the rubber/cord interface or at both in varying amounts. Afier separation has been completed, the amount of rubber remaining (B) on the cord is determined by visual inspection.

(2) Fatigue data based on heat durability was obtained on a tube of rubber reinforced with the cord treated in the manner described herein and tested in accordance with the requiremerm of ASTM D-885-59T,

Sec. 42.

The present invention may be used in the manufacture of a pneumatic tire of conventional present day design as shown, for example, in such US. Pat. Nos. as 3,157,218; 3,160,191; 3,160,192; 3,217,778; 3,225,810; 3,225,812; 3,244,215; 3,253,633 and 3,253,638 all of which show a vulcanized rubberized fabric carcass of generally torodial shape having a tread portion superimposed and bonded to the crown area of lo the carcass and plies of rubberized fabric forming sidewalls extending from the tread over the carcass to the bead portion.

While certain representative embodiments and details have been shown for the purpose of illustrating the l5 invention, it Wlll be apparent to those skilled in this art by weight of lubricating oil.

f zg h eTATEs PATENT OFFICE 1 "CERTIFICATE OF CORRECTION Patent 1N0. 31755 5 Dated August J-973 Inventor) Roop S. Bhakuni and Joseph L. Germany, Jr.

It is certified that error appears in the e'ibeve-identified patent and that said Letters Patent are hereby col-meted as shown below:

Column 1, line 38, finished" should be finish Column r, line 53', in Example 3, the amount llO has been left out in the cplumn headed "Peel Force".

7 Signed and sealed this 1st day of Octoberv 1974.

(SEAL) v Attest:

MCCOY M. GIBSON JR, 0. MARSHALL DANN Attesting Officer Commissioner of Patents 

